Bayesian inference of phylogeny is based upon a quantity called the posterior probability distribution of trees, which is the probability of a tree conditioned on the observations. the conditioning is accomplished using bayes's theorem. the posterior probability distribution of trees is impossible to calculate analytically; instead, mrbayes uses a simulation technique called markov chain monte carlo (or mcmc) to approximate the posterior probabilities of trees.

this package offers a binary compiled for parallel computation with mpi.